PHASE I: Patients receive rituximab IV on days 1 and 8, indium In 111 ibritumomab tiuxetan IV over 10 minutes on day 1 (for radioimaging), and IDEC-90Y2B8 IV over 10 minutes on day 8. Treatment repeats 24-36 weeks later for a total of 2 courses in the absence of disease progression or unacceptable toxicity. Once the maximum tolerated dose (MTD) of IDEC-90Y2B8 is determined, patients also receive filgrastim (G-CSF) subcutaneously (SC) daily beginning when absolute neutrophil count is less than 1,500/mm3 and continuing until blood counts recover. Patients also receive interleukin-11 (IL-11) SC beginning when platelet count is less than 75,000/mm^3 and continuing until blood counts recover. Patients undergo PBSC transplantation only if marrow recovery is inadequate.